How to Install a 1998 Sunfire's Thermostat

The thermostat in the Pontiac Sunfire helps regulate the engine temperature by controlling the flow of coolant through the system. When the engine temperature increases, the thermostat allows more coolant to flow, maintaining a steady temperature to prevent overheating and damage. If your Sunfire begins overheating and the coolant levels are correct, the thermostat may be failing, putting you at risk for serious engine damage.

Instructions

1

Place a large drain pan beneath the radiator drain plug on the passenger side of the car. Open the hood and remove the radiator cap.

2

Loosen the drain plug with a wrench until the coolant begins to flow. Wait while the radiator drains. Tighten the plug completely once the radiator is empty. Remove the drain pan.

3

Follow the lower radiator hose to the thermostat housing on the opposite end. Loosen the hose clamp with a flat-bladed screwdriver. Pull the hose off the thermostat housing. Using a wrench, remove the two bolts securing the thermostat housing.

4

Pull the cover off the thermostat housing and remove the thermostat and o-ring. Install the new o-ring provided with the new thermostat. Insert the thermostat and replace the housing cover. Secure the housing with the bolts, tightening them with a wrench.

5

Push the lower radiator hose onto the thermostat housing. Tighten the hose clamp with a flat-bladed screwdriver. Fill the radiator with a 50-50 blend of antifreeze and distilled water.

6

Start the engine and let it idle. Pour more coolant into the radiator if the level drops while the car is warming up. This purges air from the cooling system. Turn on the heater once the engine is warm. Let it idle for 2 to 3 minutes. Turn the ignition off and wait for the engine to cool.

7

Add additional coolant to the radiator if needed once the engine is cool. Replace the radiator cap and close the hood.